Abstract: Using the process technology of precipitated silica, under the same condition, different mass fractions of hydroxy carboxylic ester were added into precursors as modifier in order to wet modification, the mechanical properties, dynamic properties and dynamic heat generation properties of silica/nature rubber (NR) composites were investigated. The results show that the silica prepared is amorphous silica, the dispersion of silica modified by the mass fraction of 6% of hydroxy carboxylic ester is good, particles are distributed evenly, which shapes like a ball, and some hydrophilic groups of silica are eliminated effectively by using hydroxy carboxylic esters, therefore, the dispersity of silica in NR is improved. When the amounts of silica increase, the mechanical property, loss factor and dynamic heat generation of the composites are enhanced, meanwhile, the Payne effects are also increased. By the time the content of silica reaches its critical value (the mass ratio of silica to NR is 40:100), the mechanical properties of silica/NR composites would have better performance, the properties of modified silica/NR composites is better than unmodified silica/NR composites, as results of the hardness and tensile strength and elongation at break are increased, the wear volume and dynamic heat generation are decreased. Dynamic mechanical performance test shows that when the mass ratio of modified silica to NR is 40:100, the rolling resistance of modified silica/NR composites loss factor at 0℃ keep almost constant, but the skid resistance of composites loss factor at 60℃ drops from 0.123 to 0.104. The results of SEM prove that better dispersion and stronger interfacial interaction are achieved in NR matrix filled by modified silica than unmodified silica.